Ball deflector for ball screws



March 5, 1957 I J. A. FISHER BALL DEFLECTOR FOR BALL SCREWS Filed Dec. 19. 1955 INVENTOR. JOHN A. FISHER A T TORNEY BALL DEFLECTOR FOR BALL SCREWS John A. Fisher, Maple Heights, Ohio, assignor to The Cleveland Pneumatic Tool Company, Cleveland, Ohio, a corporation of Ohio Application December 19, 1955, Serial No. 553,7 85

Claims. (Cl. 74-459) This invention relates generally to antifriction ball screw and nut devices and more particularly. to a new and improved deflector which is used to deflect the balls into and out of the return tube as the screw and nut rotate relative to each other.

It is an important object of this invention to provide a deflector element for use within the nut of a ball screw device which is compressed by the groove of the nut so that it is retained within the groove by the reaction force of deflection in combination with an anchoring hook which is positioned within a recess in the wall of the nut which prevents the deflector element from moving along the groove.

Further objects and advantages will appear from the following description and drawings, wherein:

Figure 1 is a side elevation partially in longitudinal section showing a ball screw and nut incorporating dcflector elements according to this invention;

Figure 2 is a cross sectional view taken along 2-2 of Figure 1; and,

Figure 3 is a cross section of a nut incorporating a second embodiment of the deflector element according to this invention.

Referring to the drawings, an antifriction ball screw and nut device incorporates a screw formed with a helical groove 11 which cooperates with a helical groove 12 formed in a nut 13 to form a helical passage. A plurality of antifriction ball bearings 14 are positioned within the helical passage and interconnect the nut 13 and screw 10 in a manner wherein relative rotation between the nut and screw produces relative axial motion therebetween. When there is relative rotation between the nut 13 and screw 10, the balls roll along the surface of the grooves 11 and 12 and progress to one or the other of the ends of the nut. Therefore means must be provided to convey the balls 14 between the ends of the nut to produce a closed circuit. To that end, a return tube 16 is mounted on the nut 13 so that the ends of the return tube connect to opposite ends of the nut. The ends ofthe return tubes are positioned within the first bores 22 which are co-axial with second bores 23 that form a continuation of the return tube passage and connect the return tube with the helical passage.

Positioned within the groove 12 of the nut 13 adjacent to each end of the return tube 16 is a deflector element 18. The deflector elements are partly circular, preferably formed from resilient rod stock and propertioned so that when they are positioned within the groove 12 they are compressed from an unstressed condition. Therefore a resilient reaction force is produced which urges the deflector elements 18 into engagement with the surface of the groove 12 and assures a close and tight fit of the element within the groove. The deflector elements 18 are formed so that they have a circular portion 19 which extends along the surface of the groove 12 through more than 180. One end of each deflector element is formed with an inclined deflecting surface 21 which engages the balls within the helical passage as they approach the end of the return tube 16 and deflect cess or radial bore 26 formed in'the nut 13.

be understood that it is preferable to use a bore 26 which the balls from the helical passage into the-return tube. It should be understood that both of the deflector elements are similar and that when one operates to deflect balls into the return tube, the other operates to deflect balls from the return tube into the helical passage.

The end of each deflector element opposite from the deflecting surface21 is formed with a hook portion 24 extending radially outward and positioned within a reextends completely through the wall of the nut since it is the easiest form to manufacture. However, any recess which provides radially extending walls to be engaged by the hook portion '24 will serve the function of anchoring the deflector element 18 against motion along the surface of the groove 12.

To assemble the deflector elements 18 within the nut, it is necessary to compress the deflector element so that it may be positioned within the groove with the hook by the walls of the groove 12. The spring action of the deflector element will also hold the hook portion 24 in radial bore 26. If it becomes necessary to remove the deflector element 18 from the nut, pressure can be applied to the hook portion 24 through the bore 26 to unhook the deflector after which it can be threaded out of the nut. Because the hook portion 24 positively prevents the deflector from sliding along the groove, the defiector does not have to be formed so that thereis an excessive engagement pressure between the deflector element and'the surface of the groove 12 to secure the deflector in place. Those skilled in the art will recognize that'by the use of a deflector element according to this invention, an economical easily assembled mecha nism may be manufactured.

In Figure 3 another form of deflector element 27 is shown. In this case the deflector element is provided with a deflecting surface 28 and a hook portion 29 similar to the first embodiment. However, the circular portion 31 is cut away to form a relief 32 which reduces the rigidity of the deflector elements so that it may be more easily compressed for insertion within the nut. It should be recognized that although the preferred deflector element is formed of rod stock, stamping or other methods of manufacture may be used so long as the resulting deflector element operates in the manner taught by this invention.

Although preferred embodiments of this invention are illustrated, it will be realized that various modifications of the structural details may be made without departing from the mode of operation and the essence of the invention. Therefore, except insofar as they are claimed in the appended claims, structural details may be varied widely without modifying the mode of operation. Accordingly, the appended claims and not the aforesaid detailed description are determinative of the scope of the invention.

I claim:

1. In a device of the character described a member formed with helical groove, means formed with a recirculating passage connecting the ends of said groove, and an arcuate resilient deflector element adjacent to each end of said recirculating passage providing a surface adapted to deflect antifriction members between said groove and recirculating passage, said elements engaging the wall of said groove through more than ,rfatentea 5, 1951 It should n 3,788,656 ,7 e V i mass ssapiaas' saia eieaa s froni their unstressed position whereby said elements -are*resiliently'urged into" engagement with the walls of said groove, said elements and an a'rc'iiatei .r'esiliiit' deflecfof eie'rheiit sun-sear to each end; of said recirculating passage providing a stirface' adaptedto' deflect antifi-ietioii nemesis between said roove aiifd'ree'iiculating, assage, said deflector elements e g'ing'said gronvetfiiongn mor tHanII'SOFwitEsaid ment c'onipi srfigsaida de e'ctor' eleiiieiits train their unstressed panties whereby the are resiliently. urged ism engage ent witntne vfvans erjssia: groove,- :1 i inth walljo'f saia nut for menisc -er, portion on eaelidefletor'elefii ent extending into f said" apertures 'th'fereiiyfi fvntifig "movement or" deflector elements along said grease; 3. In a device of thecharacferjdes'ciibd anu't' forni'ed viiili an internal helical groove, means fdrn'iediwitii a recirculatin passage connee'ting'the ends of said groove; ah an a'rc'u'at'e resilient" deflector l melit adjacent to eacii'erid of said recirculating pas" ge' providing ahend surface adapted to deflect antifrict o'n members between g eve and recirculating passage, saiddefieet'or are ts engaging said gioave' through more 180 w th said engagifient conipressih'g said deflector e16- meats froin' their uns'tresse'd' position whereby tlivj' are n ti'y"u'rg'e'd into e ga entwiththe walls'of said groove} an aperture in the wallet "said nut 'forieaciildenee r and a hook'port'ionon the end of said defleetbr eiehie opposite said'end snrfa'ce'exfeiiding into onebf sa d aper s thereby prevent'ingimoveni'ent of said dene wietements slan 'said grnove.

4. A ball serew corfiprising new and nut baa-1 formed with fat helical groove which mutually cooperate to define a helical passa e, a plurality at antiiriction 'r'nerrib'ers in said passage interconnecting said nut and screw whererelative rotation between said nut and screw produe'es r'elativeaxialniotion therebetween, a return tube on said nut connecting the ends of said passage forming a closed circuit of antifriction members, and a deflector element positioned in said nut groove adjacent to each end of said passage formed with a surface adapted to deflect said antifriction members: between said passage and said return tube, eachdeflectorelernent engaging said nutgr'ciov' thriiiigii rrio're than iso anabemg compressed thereby fron'i-iits unstressed position, a recessin said nut'for eacli deflector, said defleeters'being formed with hook portions extending into saidrecesses reventing movement of: said deflectors-along. said nut groove.

5'. A Ball screw comprising screw and nut each formed with a helical groove'which 'inufualiy cooperate to define a helicai passage, a plurality of antifriction members in said passage interconnecting said nut and screw whereby-relative rotationmbetween. said nut and screw pioducesiel'a'tive iiirial rriotioh therebet ween, a return tube on saidbut. coriheotingthe ends-of said passage fanning a; dosed circuit of antifriction members, and a defiec'to'ielenient positioned insaid nut groove adjacent to each end of said passage formed with a surface adapted to deflect sat ritifriction-rnenibei's between said passage and said ieturii tube, each deflector element engaging said not @0696 through more than i and being compressed hereby frofn its unstressed position, a portion crisis. defeats} elements im'er'mediaie its ends, being fornadldf'feduced' cross section to decrease the force necessary to cbfnpress it from the unstressed position, arecess incsaid nut for each deflector, said deflectors being fo'iindwi tiihook portions extending. into said reces's'es preventingifiioven'ient'of said deflectors along said niit'gioove.

Means s- Apr. 25, r959 Jaeun'ema Apr.- 28, 1953 i' r bsiia'ii 2,636,397 

